Sectaria graffiti has appeared outside Hampden Park just hours before the Betfred Cup final between Rangers and Celtic.
A box was spray painted "fenian b*******" just yards away from the national stadium .
Furious fans from both teams took to social media to share the snap and condemn those responsible for the vandalism .
Glasgow City Council said they would send a team to the stadium to clean the graffiti if it is reported.
A Glasgow City Council spokeswoman said: "If sectarian graffiti is reported to us we will send a team down to clear it up."
Police Scotland have not been made aware of the graffiti.
It comes a day after the derogatory slur "f*** huns" was daubed across a sign at the entrance to the Hummel Training Centre at Auchenhowie .
Rangers vowed to comb through CCTV footage to find those responsible.
A Rangers spokesman said: "We will examine CCTV footage to see if those people responsible can be identified.
"Sectarianism in whatever form it takes is unacceptable."
